Analog Devices EVAL-AD9959 User Manual page 10

User Guide
EVALUATION BOARD SOFTWARE
System Clock displays the operating frequency the DDS core
(system). The value shown here is derived from the values entered
in the Ref Clock and Multiplier boxes.
VCO Gain is automatically set when the Ref Clock Multiplier is
being used to generate a system clock that is greater than 255
MHz. This is done to ensure stability of the Ref Clock Multiplier
circuitry. A pop-up window will appear alerting you to this update
(see Figure 20).
Figure 20.
Refer to the Reference Clock Modes section of the
sheet for more information regarding clock modes and operation.
3. All Channel Accumulator Control
The All Channel Accumulator Control provides control over the
phase and sweep accumulators for all channels.
Check the Auto Clear Phase Accumulator or Auto Clear Sweep
Accumulator boxes to clear and release the corresponding accu-
mulator. The auto clear function sets the accumulator to 0 and then
begins accumulating.
Select the Clear Phase Accumulator or Clear Sweep Accumula-
tor to clear and hold the corresponding accumulator. The clear
function clears and then holds the contents of the corresponding
accumulator to 0 until the box is unchecked.
4. Modulation Configuration
The Modulation Configuration section configures the modulation
operation of the AD9959.
Profile Pin Configuration provides access to the PPC Bits
(FR1<14:12>). These bits are used to control the modulation
scheme of the AD9959. PPC Bit 0 is the LSB (FR1<12>), and
PPC Bit 2 is the MSB (FR1<14>).When a PPC bit is selected, it is
set to Logic 1 from its default setting of 0. These bits are discussed
in more detail in the Modulation Mode
RU/RD assigns which pins will control the scaling (Ramp Up/Ramp
Down) of the output amplitude of the AD9959. This feature can be
controlled via the profile or SDIO data pins.
Select Use Profile Pins 2 & 3 if you would like to control the
RU/RD feature with Profile Pin 2 and Profile Pin 3, or Use Profile
Pin 3 to control this feature using only Profile Pin 3. If you wish to
use the SDIO data pins to control this feature, simply select Use
SDIO pins 1, 2, & 3. Note that to use the SDIO pins to control the
analog.com
AD9959 data
section of the data sheet.
RU/RD feature, the SDIO RU/RD Control jumpers must be placed
(see Figure 2). The default setting of this box is RU/RD Disabled.
In this mode, you will not be able scale the output amplitude.
The AD9959 can be configured to perform many operations in
various combinations. Please refer to the Channel Constraint
Guidelines and the Modulation Mode sections of the AD9959 data
sheet for more details regarding the use of the RU/RD function
in combination with the different modes of operation (single-tone,
modulation, linear sweep) of the AD9959. For more information
regarding the theory of the RU/RD operation, note the Output
Amplitude Control Mode section of the AD9959 data sheet.
Level selects the desired level of modulation of the AD9959. The
AD9959 can perform 2-level, 4-level, 8-level, or 16-level modulation
of frequency, phase, or amplitude (FSK, PSK, ASK). This modula-
tion is controlled via the data pins; note the Channel Constraint
Guidelines and the Modulation Mode sections of the AD9959 data
sheet for more details.
5. Multi Device Sync
It is possible to synchronize multiple evaluation boards. Refer to the
Synchronizing Multiple AD9959 Devices section in the AD9959 data
sheet and the evaluation board schematic (located in the schematic
folder of the AD9958_59 evaluation software CD) for more details
on synchronizing multiple AD9959s.
6. All Channel Power Down
The All Channel Power Down section allows you to power down all
channels collectively using software configurations or the external
power down options found in the External PD Control subsection.
Select the Clock Input, DAC Ref, or Disable SyncCLK Out boxes
to power down those circuit blocks respectively for each individual
channel. Once the selection has been made, click the LOAD button
to execute the power down.
When using the External PD Control, select from the Power
Down Pin Mode: Quick Recovery (default setting) or Full Power
Down mode. In quick recovery mode, only the digital logic is pow-
ered down whereas all functions are powered down in full power
down mode. To execute the power down when using external PD
control, you must click the Power Down Pin. When pressed, the
power down pin is at Logic 1, indicating the powered down mode.
When this pin is not pressed, it is at Logic 0, indicating the powered
up mode.
EVAL-AD9959
Rev. A | 10 of 27